The steps involved in RNA tumor virus replication via a DNA intermediate are unknown. The primary objectives of these studies are to investigate the in vitro and in vivo mode of avian RNA tumor virus DNA synthesis. These studies include: (1) continue detailed analysis of the structural, catalytic, and functional properties of the alpha and alpha-beta DNA polymerase with their associated ribonuclease H (RNase H) activity isolated from avian myeloblastosis virus (AMV); (2) investigate the possible role of the various internal ribonucleoproteins of AMV as well as cellular proteins from natural and virus-infected cells in viral DNA synthesis; (3) to isolate and characterize the intracellular "reverse transcriptase-viral RNA complex" in different virus-infected cells; (4) in vivo studies characterizing new proviral DNA synthesis and its integration into the host chromosomes; and (5) development of a cell culture system for growth of avian tumor viruses.